The KBSS-KCWI Survey: The connection between extended Ly$\alpha$ halos and galaxy azimuthal angle at $z\sim 2-3$

Understand

We present the first statistical analysis of kinematically-resolved, spatially-extended Ly$\alpha$ emission around $z = 2-3$ galaxies in the Keck Baryonic Structure Survey (KBSS) using the Keck Cosmic Web Imager (KCWI).

• Our sample of 59 star-forming galaxies ($z_\mathrm{med} = 2.29$) comprises the subset with typical KCWI integration times of ~5 hours and with existing imaging data from the Hubble Space Telescope and/or adaptive optics-assisted integral field spectroscopy.
• The high resolution images were used to evaluate the azimuthal dependence of the diffuse Ly$\alpha$ emission with respect to the stellar continuum within projected galactocentric distances of $\lesssim 30$ proper kpc.
• We introduce cylindrically-projected 2D spectra (CP2D) that map the averaged Ly$\alpha$ spectral profile over a specified range of azimuthal angle, as a function of impact parameter around galaxies.